1. Field of the Invention
The present invention relates to an image display system, and more particularly, to a head up display for vehicles which is viewed through a specular or partially specular reflection surface.
2. Description of the Prior Art
Conventionally, the projector is often used in the meeting, business briefing, teaching and training. During the recent years, the technology of imaging module and display, such as the Liquid Crystal Display (LCD), Digital Light Processing (DLP) or Liquid Crystal on Silicon (LCOS), progress very rapidly. Therefore, the products which combine the imaging module and the display are increasingly applied for versatile fields, for example, the home drama, helmet display, small portable display and Head-Up Display (HUD).
Normally, the conventional projection displays project images onto a reflective surface or a screen, which have a diffusive reflection characteristic. Thus, their applications are very limited.
Head up display (HUD) is originated from the aviation technique, but the conventional aviation HUD is complex and bulky, and its setup location and magnification are fixed and unadjustable, and such that it is very expensive.
Along with the advancing of technology, presently the HUD is more and more popular for the application of automobile, but the HUD for vicheles uses traditional direct-view display as the image source, whose angular emission profile is highly diffusive which results in low brightness or requires high driving power to meet a specified brightness.